In “Prime Suspect 2,” Helen Mirren has one of those rare women’s parts: a heroic one. She gets to be clever, sensitive and brave. As Detective Chief Inspector Jane Tennison, Mirren solves murders, battles sexism and stares down evil with more conviction than Columbo and Sherlock Holmes combined.

“What initially attracted me to Tennison,” says Mirren, “was that she drove the story. And that’s very uncommon. If you think of a character like the one Meryl Streep played in `Sophie’s Choice’ – it’s a wonderful role but she doesn’t actually drive the story. This is a thriller and the real motor of the story is a woman. Tennison is not someone who something is being done to.” Indeed. Like Jodie Foster’s Clarice Starling in “The Silence of the Lambs,” Tennison must match wits with a monster. When the decomposed body of a young woman is uncovered in an alley in London’s Afro-Caribbean community, Tennison is called upon to head the investigation.

“Prime Suspect 2” “is not about breaking into people’s houses with guns,” says Mirren of the four-part program which will begin airing at 9 p.m. Thursday on PBS’s “Mystery!” series. “It’s not about that side of police work. It’s about the people back at the office using their intelligence to decide which house should be broken into and which shouldn’t.” Smart and erotic, exposed but strong, Mirren’s characters often defy stereotypes, from the classy gangster’s moll in “The Long Good Friday” to the foolishly romantic widow in “Where Angels Fear to Tread” to the victimized wife who refuses to become a victim in “The Cook, The Thief, His Wife and Her Lover.” In contrast to the rules of the movie industry, the London-born actress, who is now 47, has gotten meatier parts as she’s gotten older. No role, though, has called for such hidden reserves as the Tennison part.

“I’ve never thought of myself as having an image because my work is so contradictory,” says Mirren. “So, I wouldn’t say I was consciously looking for something that was different but I did recognize that this role was going to be pretty seminal both for me personally and, hopefully, for the ways in which women are perceived on screen.” When the first “Prime Suspect” was broadcast last season, it garnered the biggest “Mystery!” numbers of the season — a statistic Mirren chalks up to good timing. “It hit at exactly the right time,” she says, “airing as it did right after the Anita Hill hearings. It was extremely of the moment. I think a dam broke as far as women were concerned last year. We’d kept our mouths shut for 20 years about (the sexual harassment) we’ve always had to deal with. But last year, everyone seemed to say, `We’re not going to keep quiet anymore.’ And it happened everywhere, from city hall to the Senate to the Judiciary Department.”

Since the last episode of “Prime Suspect,” Tennison has won the respect of her male colleagues but she’s still battling less-experienced officers for a promotion. She continues to feel the sting of sexism but “she has more confidence,” notes Mirren. “And the people she works with are now on her side. They’re a team. And she’s very much in control of that. But I think her confidence brings her to make some fairly disastrous mistakes that almost pull her down.” All of Tennison’s mistakes involve Detective Sgt. Oswalde (Colin Salmon), a black colleague with whom she’s had a brief fling. “In (Tennison’s) eyes, it’s a one-night stand. Oswalde is someone she likes a great deal but it’s not a blazing love affair.” Tennison’s decision to cast aside Oswalde is not a matter of her being afraid of the emotional abandon that a romance might bring. “She’s not afraid of anything,” corrects Mirren. “She’s just not interested.”

Playing Tennison, a woman who is occasionally unlikable but never unsympathetic, presented the challenge of a lifetime, says the actress.

“I have a tendency to smile more than the scripts allow. It’s a habit that I myself have fallen into — smiling to be pleasing, smiling to be manipulative, smiling when you say something nasty so people don’t feel quite so bad about it. Women smile a great deal, trying so hard to be accommodating. And to learn not to smile, to show a face that bears neither a willingness to please nor a ferocious quality, is difficult.” To prepare for the role, which was created by actress-turned-screenwriter Lynda La Plante, Mirren spent a great deal of time with members of London’s police force.

“I couldn’t draw Tennison from my imagination,” explains Mirren, “because I’ve always been sort of psychologically, though not literally, on the other side of the law. I’ve always found police people intimidating and frightening. I’ve felt very uncomfortable around people in uniforms.” That changed once Mirren began researching the character. These days, she has a sympathy for those officers whose job it is to observe human behavior and make snap judgments about it. “The police do have quite a lot in common with actors,” says Mirren. “The only difference, really, is that police people are better at acting than actors are. They have to be: They’re doing it out there in real life. There’s certainly no editing room floor for their mistakes to be cut up and thrown away. Speaking of acting, when I watch (the syndicated series) `Cops,’ I see these policemen being so nice, so understanding, they’re like these saints. They’re so reasonable, calling everyone `sir’ and `ma’am.’ What a performance! You know, the minute those cameras are gone, it’s a whole different thing.”

Like Tennison, Mirren is something of a workaholic. “I’ve always enjoyed my work and, basically, I’ve wanted to do it more than anything else. So to that extent, I am very similar to her. But I’m not that obsessive. I’m not so ruthless. Certainly not so ruthless. And I know I could never be a police officer because of the miserable nature of the world they have to deal with every day.” And while Tennison has difficulty maintaining a personal life, Mirren has been involved for the last eight years with Taylor Hackford, an American filmmaker with whom she worked on the 1985 thriller “White Nights.”

Though she declines to discuss Hackford, she doesn’t rule out the possibility of collaborating with him again. “It is a tough thing to work with the person you’re living with,” says the never-married Mirren, who has also been linked with actor Liam Neeson. “You’ve got to have great understanding and a terrific sense of humor. It’s certainly not something that I’m dying to do. But it might be wonderful. When I did work with Taylor, it was wonderful.” Since making Los Angeles her part-time home in 1984 — she still maintains an apartment in London — Mirren has appeared in a string of American films, including “The Mosquito Coast” and “2010.” But none has made her a bankable commodity in Hollywood. Rumor has it that when Universal Pictures turns “Prime Suspect” into a motion picture later this year, Mirren won’t even be in the running for the role she created.

“A part of you goes, `Oh, yes, there you go yet again’ because this does happen all the time to good work. But that’s what Americans do: They see something that’s great and they buy it and market it. But when you’re at the other end of it, you do feel that your work is being appropriated, which certainly is not a good feeling.” Mirren fans can take consolation in the fact that the actress will return for a third “Prime Suspect” series set to begin filming this summer. (The plot is rumored to concern child pornography.) Until then, Mirren remains unsurprised by the fact that she hasn’t been approached to play any more strong characters like Jane Tennison.

“It doesn’t work like that for me, somehow. Maybe it’s because most of my work comes out of England. And also I think it’s because there are very few roles like Jane Tennison around. You can’t be asked to play more roles like her because, quite simply, there are no other roles like her. She’s one of a kind.”